In the case where a plurality of indoor systems (fan coil units) are installed in a place such as a large-scale factory or building, for example, a heat source system has been used in which heat source water (cold or hot water) is supplied from a heat source to these indoor systems for air conditioning of plural air-conditioning areas. This heat source system is roughly separated into a heat source side and a load system side (an indoor system side), which are connected to each other through a water supply pipe and a water return pipe to form one circuit. By the water supply pipe, heat source water is supplied from the heat source to a load system, and by the water return pipe, the heat source water is returned through the load system to the heat source again.
For example, the heat source water subjected to heat exchange within the heat source is supplied by a primary pump through the water supply pipe to the load systems such as air conditioning systems or fan coils. This heat source water is subjected to heat exchange within the load systems and then supplied to the secondary pump through the water return pipe. The heat source water supplied to the secondary pumps goes through the heat source again, thus circulating in the circuit. Herein, generally, the heat source system is provided with a bypass pipe which bypasses the water supply and return pipes between the heat source side and load system side in order to cope with imbalance between the flow quantity of heat source water flowing in the heat source side and the flow quantity of heat source water flowing in the load system side.
At this time, in order to set temperature of the heat source water supplied to the load systems to a setting value or to operate the heat source at higher efficiency, it is desirable to adjust and equalize the flow quantity of heat source water flowing in the heat source side and the flow quantity of heat source water flowing in the load system side. For the purpose of measuring the flow quantity of heat source water flowing in the heat source side or in the load system side, in many cases, flow meters are provided both in the heat source side and load system side (see Patent Literature 1 below) or only in the load system side (see Patent Literature 2 below).